Joined fiber-reinforced composite material assembly with tunable anisotropic properties

ABSTRACT

An anisotropic composite material assembly comprising a first layer with a tensile modulus different from its compressive modulus and that exhibits variable modulus behavior. The first layer elastically buckle under compressions. A second layer has a tensile modulus substantially the same as its compressive modulus. The first and second layers are joined together, and the assembly is bendable in a first direction with an outer surface of the first layer being in compression and the assembly has a first bending stiffness during bending in the first direction. The assembly is bendable in a second direction opposite the first direction with the outer surface of the first layer being in tension, and the assembly has a second bending stiffness greater than the first bending stiffness during bending in the second direction.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This patent application is a continuation of U.S. patent applicationSer. No. 15/942,259, titled Joined Fiber-Reinforced Composite MaterialAssembly with Tunable Anisotropic Properties, filed Mar. 30, 2018, whichis a continuation of U.S. patent application Ser. No. 15/220,352, titledJoined Fiber-Reinforced Composite Material Assembly with TunableAnisotropic Properties, filed Jul. 26, 2016, which claims the benefit ofand priority to U.S. Provisional Patent Application No. 62/262,335,titled Composite Beam Construction with Tunable Anisotropic Properties,filed Dec. 2, 2015, each of which is incorporated herein in its entiretyby reference thereto.

TECHNICAL FIELD

This application relates in general to anisotropic materials, and, inparticular, to composite beam construction with tunable anisotropicproperties, including assemblies incorporating the composite beamconstruction.

BACKGROUND

In general, materials are isotropic or anisotropic. Isotropic materialshave identical properties in all directions. Conversely, properties ofanisotropic materials are directionally and geometrically dependent.

Conventionally, in applications that require the use of materials thatpermit bending, materials such as metal, polymers, or composite can beused to form flexural beams. The modulus of the materials used in thebeams and their geometry influence the stiffness. Depending on thematerial used to construct the beam, the beam can have isotropic oranisotropic properties. Nevertheless, beams constructed with suchmaterials have an inherent inability to exhibit a low bending resistancein one direction and a high bending resistance in the other.Furthermore, these materials exhibit a linear relationship betweenstress and strain.

Many products, such as consumer products, including footwear andapparel, medical devices, medical appliances, manufacturing products,and many other products, incorporate materials to provide a selecteddegree of stiffness while still allowing for some flexibility forbending during use. However, oftentimes, desired characteristics withina shoe or other similar products can be at odds with other desiredcharacteristics. For example, footwear often incorporates materials thatallow the sole assembly to bend and flex with a wearer's foot duringuse, while also providing a desired level of protection and structuralstability to the foot. For example, a sole assembly construction thatprovides enhanced flexibility is often provided at the sacrifice ofstructural stiffness and or stability. Conversely, the use of materialsto provide enhanced structural stiffness and stability are often at thesacrifice of flexibility.

In materials with a linear relationship between stress and strain,stiffness is constant. However, in many applications, materials thatincrease stiffness as a function of strain are desirable. For example,in some products such as footwear, it is desirable to allow the footwearto bend in the toe region to allow the wearer's toes to bend through anormal range of motion. It is also desirable, however, for the footwearto provide a stiffness that prevents the toe region from bending pastthe normal range of motion resulting in a condition of increased strain,thereby avoiding hyperextension of the wearer's toes (i.e., turf toe).Similarly, it is desirable to provide a brace or other medical appliancethat allows for bending or articulation of a portion of a wearer's bodythrough a normal or selected range of motion. It is also desirable,however, to provide a stiffness that prevents articulation of the bodyportion beyond the normal or selected range of motion, which wouldcreate a condition of increased strain. The present technology canachieve this desirable configuration that increases stiffness as afunction of strain.

Linear stiffness behavior and tradeoffs between competing performanceand operating characteristics is often encountered in the manufacturerand/or use of a wide variety of products. Accordingly, there is a needfor a material suitable for applications requiring variable modulusmaterial (i.e. anisotropic flexural material or strain stiffeningmaterial).

SUMMARY

An embodiment of the present technology provides a joined,fiber-reinforced composite material assembly with tunable anisotropicproperties. The assembly of an embodiment is configured to exhibit a lowresistance to bending in one direction and a high resistance to bendingin the other direction. At least one embodiment provides an assemblyusable in footwear, athletic equipment and/or other products.

An embodiment of the present technology provides an anisotropiccomposite material assembly comprising a first layer having a firsttensile modulus and a first compressive modulus lower than the firsttensile modulus, such that the first layer of the assembly is configuredto elastically buckle under compression. A rigid second layer is fixedlyjoined to the first layer. The assembly is elastically bendable in afirst direction with an outer surface of the first layer being incompression, and the assembly has a first bending stiffness duringbending in the first direction. The assembly is elastically bendable ina second direction opposite the first direction with the outer surfaceof the first layer being in tension. The assembly has a second bendingstiffness greater than the first bending stiffness during bending in thesecond direction.

Another embodiment of the present technology provides an anisotropiccomposite material comprising a first layer having a first tensilemodulus and a first compressive modulus less than the first tensilemodulus. The first layer of the assembly is configured to elasticallybuckle under compression. A second layer is joined to the first layer.The second layer has a second tensile modulus and a second compressivemodulus substantially the same as the second tensile modulus. Theassembly is bendable in a first direction with an outer surface of thefirst layer being in compression, wherein the assembly has a firstbending resistance during bending in the first direction. The assemblyis bendable in a second direction opposite the first direction with theouter surface of the first layer being in tension, and the assembly hasa second bending resistance greater than the first bending resistanceduring bending in the second direction.

Another embodiment provides an anisotropic composite material assembly.The assembly has a first layer comprising at least one fiber-reinforcedcomposite material with fabric having first fibers interlaced withsecond fibers at a selected angle relative to each other. An elasticallydeformable matrix encapsulates the fabric. The first layer has a firstmodulus of elasticity in tension (i.e., first tensile modulus), andfirst or second fibers of the fiber-reinforced composite material areconfigured to elastically bend and buckle under compression loads on thefirst layer. A second layer is joined to the first layer at anintermediate interface area. The second layer comprises a rigid materialhaving a second modulus of elasticity in tension (i.e., second tensilemodulus) greater than or equal to the first tensile modulus. In anotherembodiment, the second tensile modulus can be less than the firsttensile modulus. The assembly is bendable about an axis in a firstdirection that puts the first layer in tension and the second layer incompression. The assembly has a first bending stiffness when theassembly is bent in the first direction. The assembly is bendable aboutthe axis in a second direction substantially opposite the firstdirection, and bending in the second direction puts the second layer intension and the first layer in compression causing the first or secondfibers to elastically buckle. The assembly has a second bendingstiffness less than the first bending stiffness when the assembly isbent in the second direction.

Another embodiment provides an anisotropic composite material assemblyhaving a first layer with a fiber-reinforced composite material withfabric, and an elastically deformable matrix encapsulating the fabric.The first layer has a first tensile modulus, and the fiber-reinforcedcomposite material is configured to elastically bend and buckle undercompression loads in the first layer. A second layer is joined to thefirst layer and has a second tensile modulus less than or equal to thefirst tensile modulus. The second tensile modulus can be greater thanthe first tensile modulus. The assembly bends in a first direction thatputs the first layer in tension and the second layer in compression, andthe assembly has a first bending stiffness when the assembly is bent inthe first direction. The assembly bends in a second directionsubstantially opposite the first direction that puts the second layer intension and the first layer in compression causing the first layer tobuckle. The assembly has a second bending stiffness less than the firstbending stiffness when the assembly is bent in the second direction.

Another embodiment provides an anisotropic composite material assemblywith a first layer having a first fiber-reinforced composite materialwith fibers impregnated with matrix, wherein the first layer has a firsttensile modulus and a first compressive modulus less than the firsttensile modulus. The fiber-reinforced composite material is configuredto bend and elastically buckle under compression loads in the firstlayer. A second layer comprises a second fiber-reinforced compositematerial joined to the first layer. The second layer has a secondtensile modulus greater than or equal to the first tensile modulus, andthe second layer has a second compressive modulus substantially the sameas the second tensile modulus. The second tensile modulus can be lessthan the first tensile modulus. The assembly bends in a first directionthat puts the first layer in tension and the second layer incompression, and the assembly has a first bending stiffness when theassembly is bent in the first direction. The assembly bends in a seconddirection substantially opposite the first direction that puts thesecond layer in tension and the first layer in compression causing thefirst layer to elastically buckle. The assembly has a second bendingstiffness less than the first bending stiffness when the assembly isbent in the second direction.

Another embodiment provides an anisotropic bendable plate assemblycomprising a first layer of flexible material having a plurality ofarranged fibers, wherein the first layer has a first rigidity, a firsttensile modulus, and a first compressive modulus lower than the firsttensile modulus. A rigid second layer is fixedly connected to the firstlayer in a substantially parallel orientation. The second layer has asecond rigidity greater than the first rigidity. The plate assembly iselastically bendable in a first direction with an outer surface of thefirst layer being in compression, and with the plurality of arrangedfibers elastically buckled. The plate assembly is elastically bendablein a second direction opposite the first direction with the outersurface of the first layer being in tension. The plate assembly has afirst bending stiffness during bending in the first direction and asecond bending stiffness greater than the first bending stiffness duringbending in the second direction.

Another embodiment provides a sole assembly for an article of footwear.The sole assembly has an outsole, a midsole coupled to the outsole, andan anisotropic plate assembly positioned adjacent to the midsole. Theplate assembly comprises an upper layer having a first rigidity, a firsttensile modulus, and a first compressive modulus different than thefirst tensile modulus. The upper layer is configured to elasticallybuckle under compression. The upper layer has a plurality of arrangedfibers at least partly encapsulated in a matrix material. A rigid lowerlayer has a second rigidity greater than the first rigidity, and has asecond tensile modulus and a second compressive modulus substantiallythe same as the second tensile modulus. A thermoplastic film is betweenthe upper and lower layers. The upper and lower layers are joinedtogether at an interface area defined by the thermoplastic film. Theplate assembly is elastically bendable in opposing first and seconddirections. An outer surface of the upper layer is in compression duringbending in the first direction and in tension during bending in thesecond direction. The plate assembly has a first bending stiffnessduring bending in the first direction and a second bending stiffnessgreater than the first bending stiffness during bending in the seconddirection.

Another embodiment provides an anisotropic composite material assemblythat comprises a first layer comprising a plurality of sheets of fabricjoined together and each having first fibers interlaced with secondfibers at a selected angle relative to the each other. The first layerhas a first rigidity, a first tensile modulus, and a first compressivemodulus. At least the first or second fibers in the plurality of sheetsof fabric are configured to elastically buckle under coplanarcompressive loads. A rigid second layer is joined to the first layer atan intermediate interface area. The second layer has a rigid materialwith a second rigidity greater than the first rigidity, and has a secondtensile modulus and a second compressive modulus. A thin intermediatefilm at the intermediate interface area is affixed to the first andsecond layers. The assembly is elastically bendable about an axis in afirst direction that puts the first layer in tension and the secondlayer in compression, and the assembly is elastically bendable about theaxis in a second direction opposite to the first direction that puts thefirst layer in compression and the second layer in tension. The assemblyhas a first bending stiffness when the assembly is bent in the firstdirection and a second bending stiffness less than the first bendingstiffness when bent in the second direction.

Still other embodiments of the present invention will become readilyapparent to those skilled in the art from the following detaileddescription, wherein is described embodiments of the invention by way ofillustrating the best mode contemplated for carrying out the invention.As will be realized, the invention is capable of other and differentembodiments and its several details are capable of modifications invarious obvious respects, all without departing from the spirit and thescope of the present invention. Accordingly, the drawings and detaileddescription are to be regarded as illustrative in nature and not asrestrictive.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the technology introduced herein may be better understoodby referring to the following Detailed Description in conjunction withthe accompanying drawings, in which like reference numerals indicateidentical or functionally similar elements.

FIG. 1A is an isometric view of a fiber-reinforced composite materialassembly with tunable anisotropic properties shown in a planar,un-flexed configuration in accordance with an embodiment of the presenttechnology.

FIG. 1B is a schematic side elevation view of the assembly of FIG. 1Ashown in phantom lines in an upward deflection configuration anddownward deflection configuration.

FIG. 2 is a schematic illustration showing, by way of example, athree-point bend of a simple beam made of the assembly of FIG. 1Apositioned in a first orientation.

FIG. 3 is a schematic illustration showing, by way of example, athree-point bend of the simple beam of FIG. 2, wherein the assembly isin an upside down configuration with the bend in the opposite directionof FIG. 2.

FIG. 4 is an enlarged cross sectional view taken substantially alongline 4-4 of FIG. 1A showing the top and bottom layers of the assembly inaccordance with an embodiment of the present technology.

FIGS. 5-8 are graphs showing, by way of example, the differences betweenflexural moduli in exemplary testing configurations.

FIG. 9 is a graph showing, by way of example, the flexural moduli of anassembly in tensions and compression.

FIG. 10 schematic illustration showing, by way of example, controlledbuckling in a non-rigid carbon fiber material under compression.

FIGS. 11A and 11B are illustrations showing, by way of example, changesin fiber orientation when composite fiber material in the assembly ofFIG. 1A is strained along the longitudinal axis of a segment of thematerial in accordance with an embodiment of the present technology.

FIG. 12 is a schematic side view of an article of footwear with a soleassembly that includes a laminate plate made of the assembly of FIG. 1A.

FIG. 13 is a schematic cross-section of the sole assembly of FIG. 12 inaccordance with one embodiment.

FIG. 14 is a schematic isometric view of a shoe insole made with ajoined, fiber-reinforced composite material assembly with tunableanisotropic properties in accordance with an embodiment.

FIG. 15 is a schematic side view of the insole of FIG. 14 supporting awearer's foot.

FIG. 16 is a graph showing the relationship of the flexural modulus as afunction of shoe torque and angle of curvature.

FIG. 17 is a cross-sectional view showing the construction of the shoeinsert of FIG. 16.

FIG. 18 is a diagram showing the layered construction of the non-rigidflexible carbon fiber composite.

FIG. 19 is a diagram showing the layered construction of a compositelaminate.

FIG. 20 is a diagram showing, by way of example, column bending in anon-rigid carbon fiber material.

FIG. 21 is a diagram showing the layered construction of a laminatestack.

FIG. 22 is a diagram showing the change in length of each layer in thelaminate stack of FIG. 21 as the radius changes from an original naturalorientation.

FIG. 23 is a diagram showing the layered construction of the carbonfiber joined plate.

FIG. 24 is a diagram showing a heat forming tool for use with the carbonfiber joined plate of FIG. 23.

FIG. 25 is a graph showing, by way of example, the differences betweenflexural moduli in exemplary testing configurations.

FIGS. 26A-B are illustrations showing, by way of examples, controlledcurvature in columns in a non-rigid carbon fiber material underpre-compression through thermally controlled contraction, by pre-formingto a predetermined engagement angle and by segmented wedges withcombined angles achieving 56° flex angle and fully engaging thenon-rigid carbon fiber at a predetermined lock-out angle.

The headings provided herein are for convenience only and do notnecessarily affect the scope or meaning of the claimed embodiments.Further, the drawings have not necessarily been drawn to scale. Forexample, the dimensions of some of the elements in the figures may beexpanded or reduced to help improve the understanding of theembodiments. Moreover, while the disclosed technology is amenable tovarious modifications and alternative forms, specific embodiments havebeen shown by way of example in the drawings and are described in detailbelow. The intention, however, is not to limit the embodimentsdescribed. On the contrary, the embodiments are intended to cover allmodifications, equivalents, and alternatives falling within the scope ofthe embodiments.

DETAILED DESCRIPTION

Various examples of the devices introduced above will now be describedin further detail. The following description provides specific detailsfor a thorough understanding and enabling description of these examples.One skilled in the relevant art will understand, however, that thetechniques discussed herein may be practiced without many of thesedetails. Likewise, one skilled in the relevant art will also understandthat the technology can include many other features not described indetail herein. Additionally, some well-known structures or functions maynot be shown or described in detail below so as to avoid unnecessarilyobscuring the relevant description.

The terminology used below is to be interpreted in its broadestreasonable manner, even though it is being used in conjunction with adetailed description of some specific examples of the embodiments.Indeed, some terms may even be emphasized below; however, anyterminology intended to be interpreted in any restricted manner will beovertly and specifically defined as such in this section.

FIG. 1A illustrates a fiber-reinforced composite material assembly 10with tunable anisotropic properties shown in a planar, un-flexedconfiguration in accordance with an embodiment of the presenttechnology. FIG. 1B illustrates the assembly 10 in solid lines in aflat, relaxed position, and in phantom lines in an upward deflectionconfiguration and a downward deflection configuration. The assembly 10has a first layer 12 of fiber-reinforced composite material fixedly andpermanently joined with a second layer 14 of durable, rigid substrate(i.e., polycarbonate, nylon, plastic, metal, rigid fiber-based material,elastomer, etc.) whose flexural modulus is greater than approximately20,000 psi. The joined assembly 10 is a bendable planar assembly, whichis described herein with reference to the spatial orientation as shownin FIG. 1A. Accordingly, the first layer 12 is shown in FIGS. 1A and 1Bas a top layer, and the second layer 14 is shown as a bottom layer. Itis noted that the terms “top” and “bottom” are used for purposes ofconvenience to discuss orientation, and it is to be understood that theassembly can be positioned in other spatial orientations, such as aninverted orientation to that shown in FIG. 1A, so that the first layer12 is below the second layer 14. Alternatively, the assembly 10 canexist in a contoured shape.

The assembly 10 is illustrated in FIG. 1A as a rectangular segment withopposing side edges 16 extending between opposing ends 18. The first andsecond layers 12 and 14 are fixedly joined together along a planedefined by a longitudinal axis 20 and a lateral axis 22 perpendicular toeach other. The assembly 10 is shown in a flat, planar, relaxed position(i.e., in a neutral orientation) wherein the longitudinal and lateralaxes 20 and 22 are parallel to a neutral plane extending through theassembly 10. The assembly 10 is configured in at least one embodiment asan anisotropically-flexible beam, such that the assembly 10 can be bentaway from the relaxed position in a first direction (i.e., upwardly)about the lateral axis 22 with the opposing ends 18 move upwardly. Theillustrated assembly 10 has a relatively low bending resistance tobending forces that cause the assembly 10 to bend upwardly, as seen inFIG. 1B. The beam defined by the assembly 10 is also constructed to bendslightly away from the relaxed position in a second direction oppositethe first direction (i.e., downwardly), such that the opposing ends 18move downwardly. In this downwardly bending condition, however, theassembly 10 has a substantially higher resistance to bending forces thatcause the assembly to bend downwardly. The joined, fiber-reinforcedcomposite assembly 10 can be tuned to be flexible and easily bendable inthe first direction, but being rigid and inflexible to bending in theopposite direction.

The first layer 12 can be configured to control bending characteristicsof the assembly 10 in a selected direction, (e.g., bending downwardly).In one embodiment, the first layer 12 of the assembly 10 is made of amaterial having a tensile modulus that is substantially greater than thematerial's compressive modulus. As discussed herein, reference to amaterial's modulus (tensile or compressive modulus) is referring to themodulus of elasticity of the material in tension and/or compression. Thefirst layer 12 can be a fiber-reinforced composite material havingunidirectional fibers or interlaced fiber encapsulated and/orimpregnated in a selected flexible matrix configured so the compositematerial alone is flexible and pliable or non-rigid. The fibers in thefirst layer 12 can be inorganic fibers (e.g., carbon fibers, glassfibers, ceramic, fibers, metal fibers, other fibers, and/or combinationsthereof), organic or synthetic fibers (e.g., polymer fibers such aspolyamides, polyesters, or combinations thereof), natural fibers, and/orcombinations thereof. The material of the first layer 12 can beconfigured such that the assembly 10 can exhibit strain stiffeningbehavior. Accordingly, the rate of stiffening in the material canincrease in response to increased strain. This configuration provides anassembly with asymmetric flexural characteristics.

In one embodiment, the first layer 12 can be a woven, carbon fiber-basedcomposite material having warp fiber bundles 24 substantially parallelto each other and the side edges 16. The warp fiber bundles 24 are wovenwith weft fiber bundles 26, wherein the weft fiber bundles 26substantially parallel to each other and at a selected angle relative tothe warp fibers 24 and/or the side edges 16. In the illustratedembodiment of FIG. 1A, the warp and weft fiber bundles 24 and 26,respectively, are woven at approximately a 90-degree orientationrelative to each other, although the woven fibers 24 and 26 can havedifferent fiber orientations relative to each other. The first layer 12may be made of one or more sheets of a tunable, non-rigidfiber-reinforced composite material. The first layer 12 can beconfigured with matrix material and plurality of fibers, such that thefirst layer is orthotropic. In one embodiment, the first layer 12 ismade of a stretchable fiber-based composite material, such as thematerial disclosed in U.S. patent application Ser. No. 15/135,455,titled Stretchable Fiber-Based Composite Material, filed Apr. 22, 2016,and which is incorporated herein in its entirety by reference thereto.The assembly 10 can also include tunable fiber-based composite materialswith binder-enhanced properties, such as the materials as described inU.S. patent application Ser. No. 15/179,949, titled Composite materialswith Binder-Enhanced Properties and Methods of Production Thereof, filedon Jun. 10, 2016, which is incorporated herein in its entirety byreference thereto.

The assembly 10 can be constructed as a laminate material by combining acarbon fiber epoxy plate that defines the second layer 14 with a fiberreinforced nitrile butadiene rubber and thermoplastic polyurethane filmthat defines the first layer 12. The strengths and stiffness of fibrouscomposite materials in the first layer 12 are dependent on theproperties of the type of fiber used, the orientation of the fiber, andthe resin matrix used to encapsulate and/or impregnate the fibers. Inone embodiment, the material used in the first layer 12 can be a nitrilebutadiene rubber impregnation with thermoplastic polyurethane films.Unlike the first layer 12, the second layer 14 is made of a materialthat has a tensile modulus substantially the same as its compressivemodulus. The second layer 14 can be a rigid carbon fiber epoxy plate.Other types of materials can be used in the second layer, such as steel,stainless steel, titanium, aluminum, other metal material,polycarbonate, polyamide, polyurethane, low density polyurethane,nitrile rubber, butyl rubber, and combinations thereof. The compressivemodulus of the material used in the second layer 14 must be greater thanthe compressive modulus of the material used in the first layer 12 toprovide the fiber-reinforced composite joined assembly 10 in the form ofan anisotropically-flexible beam with the necessary anisotropicproperties in compression and tension. In one embodiment, the secondlayer 14 can comprise a plate with a modulus of elasticity in the rangeof approximately 30 ksi-40,000 ksi. In another embodiment, the firstlayer 12 can be a carbon fiber layer impregnated or encapsulated with aresin matrix at 100% modulus in the range of approximately 5 psi-5,000psi. In other embodiments, the matrix of the first layer 12 can beformed of thermoplastic polyurethanes, thermoplastic elastomers,thermoplastic polyolefins, silicone, acrylates, polyamides,polyurethanes, nitrile and butyl rubbers, and styrenic block copolymers.The matrix material can be selected or configured to have a range ofmatrix properties, such as a modulus of elasticity in the range ofapproximately 5-3,000 psi. In another, embodiment the matrix can have amodulus in the range of approximately 5-2000 psi. In another, embodimentthe matrix can have a modulus in the range of approximately 5-1000 psi.In another, embodiment the matrix can have a modulus in the range ofapproximately 20-500 psi. In another, embodiment the matrix can have50-500 psi In yet another embodiment, the matrix can have a modulus inthe range of approximately 50-300 psi. The two layers 12 and 14 of theassembly 10 in the illustrated embodiment are laminated or otherwisejoined together under 200° F. to 375° F. for about ten minutes or lessto form an asymmetric beam that has high bending stiffness (moduli) inone bending direction and a low bending stiffness in the oppositedirection. In other embodiments, the two layers 12 and 14 could bejoined with other adhesive materials or using other laminatingtechniques.

FIG. 2 is an illustration showing, by way of example, a three-point bendon the assembly 10 with the first and second layers 12 and 14,respectively, forming an anisotropically-flexible beam having twodifferent moduli. The assembly 10 is shown in FIG. 2 in an invertedposition compared to FIG. 1B and corresponding to a downward bendingconfiguration as referenced above, such that the second layer 14 is incompression, and the first layer 12 is in tension. The assembly 10 isvery resistant to the downward bending loads because thefiber-reinforced composite material forming the first layer 12 has avery high tensile modulus, so when the warp and/or weft fibers 24, 26(FIG. 1A) are in tension, the fibers substantially prevent or resistexcessive bending. In one embodiment, the first layer 12 has a tensilemodulus in the range of approximately 3-5,000 ksi. In anotherembodiment, the first layer 12 can have a tensile modulus in the rangeof approximately 3-2,000 ksi, 5-2,000 ksi, 25-1500 ksi, or 100-2,000ksi,

When the assembly 10, however, is bent in the opposite direction so asto put the second layer 14 in tension, the assembly 10 is more flexible.FIG. 3 is an illustration showing, by way of example, the assembly 10 asa simple beam being bent upwardly in three-point bending (i.e., in theopposite direction as shown in FIG. 2) with the same force as applied inFIG. 2. In FIG. 3, the first layer 12 is now in compression, and thesecond layer 14 is in tension. The composite fiber material of the firstlayer 12 has a low compressive modulus and the fibers elastically buckleunder compression, such that the flexibility allows for a much greaterbending of the assembly 10 in the upward direction in response to thesame bending loads as the inverted response. In one embodiment, thecompressive modulus of the first layer 12 is sufficiently low such thatit provides a negligible resistance to bending of the assembly 10 in theupward direction (i.e., when the first layer 12 is in compression).Accordingly, the assembly 10 provides an anisotropically-flexible beamwith greater resistance to bending in one direction (i.e., when thefirst layer 12 is in tension) than in the other direction (i.e., whenthe first layer 12 is in compression and elastically buckles).

FIG. 4 is an enlarged partial cross sectional view taken substantiallyalong line 4-4 of FIG. 1A showing the first and second layers 12 and 14of the assembly 10 in accordance with an embodiment of the presenttechnology. The illustrated first layer 12 includes a non-rigid carbonfiber-reinforced composite material having two layers of fiber materialsjoined together. The thickness of the first layer 12 is substantiallythe same as the thickness of the second layer 14. In other embodiments,the first and second layers 12 and 14 can have different thicknesses.The first layer 12 is permanently affixed to the second layer 14 at amiddle interface area 30. The illustrated assembly 10 can be configuredwith a neutral bending plane 32 substantially parallel to the interfacearea 30. When the assembly 10 is bent upwardly, so the first layer 12 isin compression with the fibers buckling, the first layer 12 provides asubstantially negligible resistance to bending. The neutral bendingplane 32 is close to the middle of the second layer 14, which provideslow bending resistance to allow the assembly 10 to bend upwardly. Whenthe assembly 10, however, is bent downwardly so the first layer 12 is intension, the neutral bending plane 32 moves closer to the interface area30. The fibers in the first layer 12, when in tension, provide much morebending resistance relative to downward bending of the assembly 10.

The assembly 10 can be tuned by selecting and controlling the materialsof the first and second layers 12 and 14 to provide the anisotropicbending characteristics. For example, the characteristics can becontrolled by changing the number of sheets of fibers in the laminate inthe first layer, its matrix material, the weave of the fibers, theinterstitial layer material, the film material, fiber type(s), fibercontent, areal density of the fiber(s), etc. When the second layer 14 isa rigid composite fiber material, the bending characteristics of thesecond layer 14 can also be tuned by controlling the constituents of thelayer, including the layers of fiber, weave, matrix, etc. In otherembodiments, the second layer 14 can be made of other materials, such asmetals, plastics, or other material selected for tuning of the layer orthe assembly. In one embodiment, the second layer 14 can be formed ofshaped and/or perforated metal, plastic, or other suitably rigidmaterial.

Different configurations and combinations of carbon fiber materials canbe advantageously used in constructing the anisotropically-flexibleassembly. FIGS. 5-8 are graphs 34, 36, 38, 40 showing the differencesbetween flexural moduli in exemplary testing configurations. The x-axesrepresent strain in units of inches per inch (in/in). The y-axesrepresent stress in pounds per square inch (psi).

Referring to FIG. 5, the flexural modulus (i.e. bending stiffness) forthe non-rigid side (i.e., the first layer 12) in compression is 17,700psi, and the non-rigid side in tension is 117,000 psi, which is roughlya 6.6:1 change its flexural modulus based on bending direction.Referring to FIG. 6, a configuration that uses a single layer ofnon-rigid carbon in the first layer 12 has a flexural modulus for thenon-rigid side in compression of 177,000 psi and the non-rigid side intension of 808,000 psi, which is roughly a 4.6:1 change in flexuralmodulus based on bending direction. Referring to FIG. 7, shifting thefabric in the first layer 12, such that the angle between the warp andweft fibers 24 and 26 (FIG. 1) is greater or less than 90 degrees, canincrease the flexural modulus of elasticity in both the non-rigidcompression and tension values to 348,000 psi and 1,240,000 psirespectively, which is roughly a 3.6:1 change in flexural modulus basedon bending direction. Referring to FIG. 8, the shifted fabric in bendingwas tested to evaluate the transverse direction of the beam bending withlittle difference with the shifted fabric at 70 degrees to the off-axis,whether in tension or compression with flexural modulus values of 27,700psi and 24,400 psi respectively.

FIG. 9 illustrates a graph 42 showing the stress-strain relationship ofan embodiment of the assembly having a two layer, non-rigid carbon-fiberfabric configuration in compression and in tension. The graphillustrates the stress-strain relationship of the assembly with thefirst layer 12 in compression and the initiation of the elasticdeformation and buckling of the fibers in the non-rigid carbon fibermaterial. The flexural rigidity in the range of motion can be tunedthrough variation in moduli combinations. The moduli can be changedbased on resin matrix moduli and fabric weave pattern. FIG. 10illustrates controlled buckling in the first layer 12 formed by anon-rigid carbon fiber material under compression. By changing thematrix modulus, the buckling resistance will change, therefore changingthe compression modulus of the material. The matrix moduli can varybetween less than 5 psi to greater than 3,000 psi. The matrix contentcan also be controlled by coating, impregnating, or encapsulating thefibers with different quantities of matrices. For example, a matrixmaterial can be a dispersion that completely coats, impregnates orencapsulates all of the fibers with a low modulus resin and provides aweight gain of up to 50%, and conversely a dry fiber with no binder canbe used as the other extreme. This range provides a different effectivemodulus in tension and compression that is offered because of a binderthat fuses the fiber bundles together in random locations, while theother locations are considered to be dry fiber, whereas the air in thespace is the lower modulus matrix.

The compression modulus also changes based on the weave density in thefabric combined with the resin matrix modulus. Weave densities changethe spacing of the transverse tows, thereby changing the column lengthfor buckling in the longitudinal direction. For example, a 268 gsmfabric will have approximately 16 tows per inch, which yields a towspacing of 0.0625 inches and with a 2×2 twill pattern gives a 0.125 inchcolumn length. A 200 gsm fabric will be 12.5 tows per inch, which yieldsa tow spacing of 0.080 inches and with a 2×2 twill pattern gives a 0.160in. column length. Shorter column lengths increase the compressionmodulus and longer column lengths decrease the modulus. The size of thefiber tows can also be construed to offer columnar stiffness, whereas afiber tow size of 24K would have higher columnar stiffness than a 12Kand whereas a 3K would offer a lower columnar stiffness than the 12K andso on. The tow size effectively changes the columnar diameter based onthe size of the tow.

Referring to Table 1 (below), two sheets of 268 gsm fabric 2×2 twillwith 6% binder content joined to a rigid carbon fiber compositesubstrate has a flexural modulus for E100 on the non-rigid sidecompression is 59,700 ksi and the non-rigid side in tension is 454 ksi,which is roughly a 7.6:1 change in modulus based on bending direction. Aconfiguration that uses a single layer of non-rigid carbon in the firstlayer 12 has a flexural modulus for E099 on the non-rigid sidecompression of 295.8 ksi and the non-rigid side in tension of 875.7 ksi,which is roughly a 2.96:1 change in modulus based on bending direction.

Shifting the fabric (see FIG. 8) can increase the modulus in both thenon-rigid side compression and tension values to 348 ksi and 1,240 ksirespectively, which is roughly a 3.6:1 change in modulus based onbending direction.

TABLE 1 1 Layer 2 Layer 1 Layer 2 Layer 1 Layer 2 Layer SCF, SCF, SCF,SCF, SCF, SCF, 20 mil 20 mil 20 mil 20 mil 20 mil 20 mil HCF HCF PC PCTi Ti E099 E100 E274 E275 E276 E277 Flexural 875.666 454.009 209.142172.011 3703.806 1506.468 Modulus, Non-rigid Side in Tension 1.5-2%Strain (ksi) Flexural 295.846 59.670 55.994 26.941 2930.097 808.471Modulus, Non-rigid Side in Compres- sion 1.5-2% Strain (ksi) Modulus2.960 7.609 3.735 6.385 1.264 1.863 Ratio

Also a 268 gsm fabric 2×2 twill with 6% binder content comparingdifferent rigid substrates and 1 and 2 sheets of non-rigid carbon fiberdemonstrates the versatility and range of control of modulus levels onecan obtain. Referring again to Table 1, a single layer of 268 gsm fabric2×2 twill with 6% binder content forming the first layer 12 joined to apolycarbonate substrate forming the second layer 14 has a flexuralmodulus for E274 with the non-rigid side in compression of 56 ksi andthe non-rigid side in tension of 209.1 ksi, which is roughly a 3.7:1change in modulus based on bending direction. In comparison, E276 inTable 1 having a single layer of 268 gsm fabric 2×2 twill with 6% bindercontent forming the first layer 12 joined to a titanium substrateforming the second layer 14 has a flexural modulus with the non-rigidside in compression of 2930 ksi and with the non-rigid side in tensionof 3703.8 ksi, which is roughly a 1.3:1 change in modulus based onbending direction.

Referring to Table 1, two sheets of 268 gsm fabric 2×2 twill with 6%binder content forming the first layer 12 joined to a polycarbonatesubstrate forming the second layer 14 has a flexural modulus for E275with the non-rigid side compression of 26.9 ksi and the non-rigid sidein tension of 172 ksi, which is roughly a 6.4:1 change in modulus basedon bending direction compared to E277 in Table 1, two sheets of 268 gsmfabric 2×2 twill with 6% binder content forming the first layer 12joined to a titanium substrate forming the second layer 14 has aflexural modulus with the non-rigid side in compression of 808.5 ksi andwith the non-rigid side in tension of 1506.5 ksi, which is roughly a1.86:1 change in modulus based on bending direction.

In a further embodiment, the assembly 10 can be constructed as a resinmatrix and fiber weave material. The weave pattern on the first layer 12with a low compression modulus has one compression modulus in onedirection and a different compression modulus in a direction transverseto the first modulus in the same plane. This configuration allows theanisotropically-flexible beam to be flexed differently in the twoplanes. For example, a 2×2 twill fabric can have 16 tows per inch in thelongitudinal direction and 12 tows per inch in the transverse direction,thereby changing the columnar spacing that provides two differentcompression modulus by different buckling points.

In a still further embodiment, the assembly 10 can be constructed as aweave pattern with differing compression moduli based on weavedirection. This material changes layer orientations of the material ofthe first layer 12 to provide variable stiffness. FIGS. 11A and 11B areillustrations showing, by way of example, changes in fiber orientationwhen material is strained along the longitudinal axis of a simple beam.As disclosed in Applicant's U.S. patent application Ser. No. 15/135,455,when the fibers undergo tensile strain, the fibers align themselves inthe tension direction; conversely, when the fibers are in compressionand they shift into a more transverse direction causing the compressionmodulus to shift lower. When the assembly 10 is configured with thefirst layer 12 having a shifted fabric arrangement, the dynamic fiberorientation during flexing causes the beam to become stiffer as the beamis flexed. The assembly 10 becomes stiffer as the deflection increases.Accordingly, the asymmetric beam material composition can be modified ortuned to change performance. The various embodiments utilize a compositematerial design with combinations of high tensile modulus in tension andlow compression modulus material in compression to provide a highlyflexible one way beam, and conversely a highly rigid beam with oppositeloading.

The assembly 10 forming the anisotropically-flexible beam can be used ina wide variety of products or applications. For example, the assembly 10can be used to form a component in an article of footwear 50 shown inFIG. 12. It is known that the potential for injury to a wearer's footoften increases with increased flexibility. The protection of the footvia the footwear's sole assembly can be reduced through the use ofnon-rigid material that allows the traditional shoe to have greaterflexibility. To counter such potential reduced protection, the assembly10 can be used as a component of the footwear's sole assembly or as aninsole that provides anisotropic bending and that can provide a rigid,thin substrate layer that can laterally dissipate forces applied to thebottom or plantar side of the foot, thereby helping to protect it frominjury. The assembly 10 can also be incorporated into footwear toprovide increased flexibility substantially without sacrificingstability and protection. The resulting combination can decrease or eveneliminate user fatigue by incorporating an anisotropically-flexible solecomponent into the footwear.

The illustrated article of footwear 50 has an upper 52 shaped to receivea foot of a wearer. The footwear 50 can be a shoe, including a dressshoe, casual/life-style shoe, running shoe, cleated shoe, other athleticshoe, Oxford shoe, or other type of shoe. The footwear 50 can also be aboot, sandal, or other the like. The upper 52 is fixedly attached alongthe bottom margin to a sole assembly 54. The illustrated sole assembly54 has one or more internal joined plate assemblies 56 made of theassembly 10 of FIG. 1A in accordance with an embodiment of the presenttechnology. FIG. 13 is a schematic cross-sectional view of the soleassembly 54 with the joined plate assembly 56 shown relative to awearer's foot. The illustrated sole assembly 54 includes an outsole 58attached to the bottom portion of a midsole 60. The sole assembly 54 caninclude an insole board 62 attached to the top of the midsole 60 andpositioned to support the upper 52. The plate assembly 56 is attached tothe midsole 60 and can be shaped and sized to extend fully underfootfrom a forefoot portion 64 through an arch portion 66 to a heel portion68. The plate assembly 56 can be a one piece, full foot plate, althoughthe plate assembly 56 in other embodiments can include one or moresegments positioned in the forefoot portion 64, arch portion 66 and/orheel portion 68. The segments can be connected to each other or spacedapart when multiple segments are provided in the sole assembly 54.

The plate assembly 56 is shown embedded within the midsole 60. The plateassembly 56, however, can be positioned between the bottom of themidsole 60 and the outsole 58. In another embodiment, the plate assembly56 can be positioned between the insole board 62 and the midsole 60. Inyet another embodiment, the plate assembly 56 can be positioned atop themidsole 60 forming the insole board 62.

The plate assembly 56 is made with the joined construction having theanisotropic bending behavior during flexing to provide a low bendingresistance during flexing of the sole in the dorsal flex direction(i.e., upward bending) and a high bending resistance in the plantar flexdirection (i.e., downward bending). The anisotropically-flexible plateassembly 56 includes a dorsal layer 70 and a plantar layer 72, both ofwhich are constructed from two different types of flexible material. Thedorsal layer 70 is defined by the first layer 12 of the assembly 10 asdiscussed above, and a plantar layer 72 defined by the second layer 14of the assembly 10 as discussed above. The material used in the dorsallayer 70 has a low modulus of elasticity in compression and a highmodulus of elasticity in tension. The dorsal layer 70 is tuned to limitlongitudinal deflection in the plantar direction. The material used inthe plantar layer 72 has a rigid material whose modulus of elasticitycan be greater than, less than, or equal to the modulus of elasticity intension of the flexible material of the dorsal layer 70. The plateassembly 56 is configured to provide simultaneous improvements instability, flexibility, and protection not currently available infootwear.

Conventional footwear soles traditionally focus in one area ofimprovement at the sacrifice of another. For instance, a running shoemay increase flexibility and cushioning at the sacrifice of stabilityand protection. The increased flexibility is commonly achieved throughoutsole and midsole design that provides segments in the sole in flexingregions of the shoe. While this does increase flexibility, the torsionalstiffness can be considerably reduced, and the plantar flex protectioncan be substantively sacrificed. Another instance is a hiking boot thatoften sacrifices flexibility for increased protection and stability. Theuse of rigid materials in the construction of the sole of the hikingboot increases the stiffness while preventing foot bruising from rocksor roots on the hiking trail.

The assembly 10 in the form of the plate assembly 56 of the presenttechnology allows for highly tunable bending flexibility without thesacrifice of the stability and protection. In one embodiment, the dorsallayer 70 is laminated or otherwise securely joined to the plantar layer72, such that when the dorsal layer 70 is under compression when bendingin the dorsal flex direction, the dorsal layer 70 has a low compressionmodulus and can bend easily. Accordingly, the plate assembly 56 does notprovide too much dorsiflexive bending resistance, such as during thetransition from the flat foot stage of a stride through toe-off stageduring which the wearer's foot naturally bends at the metatarsal joints.Conversely, when forces on the sole assembly 54 bend the plate assembly56 in the opposite, plantar flex direction, the dorsal layer 70 is undertension and has a high modulus that can significantly resist suchbending. The laminate construction of the plate assembly 56 alsoprovides stability during a wearer's gait cycle by controlling thedorsiflexive motion that helps eliminate the foot's tendency to want toroll inward or outward (pronate and supinate). The increased flexibilityhelps reduce the forces required by the foot to flex the footwear 50,thereby reducing fatigue which can help increase stability.

During use of the footwear 50, such as running, walking, hiking,climbing ladders, etc., the sole assembly 54 is often subjected touneven surfaces such as rocks, sidewalk cracks, sticks, ladder rungs, orother sources of unevenness that can create localized forces applied tothe bottom of the wearer's foot. These localized forces can bruise thefoot or cause soreness or other discomfort. The sole assembly 54 withthe integrated anisotropic plate assembly 56 provides a rigid supportthat laterally displaces the localized forces through a high resistanceto bending in the plantar flex direction.

In another embodiment illustrated in FIG. 14, an insole 76 insertableinto the footwear's upper 52 (FIG. 12) can include a plate assembly 74with one or more portions having a construction substantially similar tothe assembly 10 discussed above. The insole 76 can be removably insertedwithin the upper 52 or it can be fixedly attached to the bottom portionof the upper 52. The insole 76 can be a generally planar insole. Inanother embodiment, the insole 76 can be a molded orthotic insole thatat least generally conforms to the shape of a wearer's foot. The insole76 can be a full-length insole extending under the forefoot, arch, andheel portions of the wearer's foot. In other embodiments, the insole 76can be less than a full length insole, such as a three-quarter-foot orhalf-foot insole.

The plate assembly 74 of the insole 76 has a dorsal layer 78 defined bythe first layer 12 of the assembly 10 and that includes a flexiblematerial exhibiting a modulus of elasticity tuned to limit longitudinaldeflection in the plantar direction. The insole 76 also has a plantarlayer 80 fixedly attached to the dorsal layer 78 and configured to fitsnuggly against the top of the footwear's sole assembly. The plantarlayer 80 includes the woven fibers within a matrix comprising anotherflexible material exhibiting a modulus of elasticity that iscomparatively higher than the modulus of elasticity of the flexiblematerial of the dorsal layer 78. The bottom of the insole 76 comprisingthe plantar layer 80 can be configured to generally provide cushioningof the foot, whilst the top of the insole 76 comprising the dorsal layer78 protects the foot against chafing, as well as providing a lesserdegree of cushioning. Alternatively, the insole 76 could be constructedwith just a single layer of rigid substrate on the dorsal side and twosheets or more of a flexible composite substrate on the plantar sidethat provides further flexibility. In one embodiment, the insole 76 canhave one or more durable cushioning and/or wear sheets attached to thedorsal layer 78 and/or the plantar layer 80 to provide additionalcomfort for the wearer's foot during use.

In the embodiments illustrated in FIGS. 12-14, the plate assembly 56 andthe insole 76 are generally planar assemblies with a flat neutralorientation when the bending forces are not acting on the assembly 10.Accordingly, when the assembly 10 is in the neutral orientation (shownin a substantially horizontal orientation), the dorsal layer 70/78 andthe plantar layer 72/80 are substantially not in tension or compression.When bending forces are applied to the flat assembly 10 to cause bendingaway from horizontal, the dorsal layer 70/78 and the plantar layer 72/80are in compression or tension depending on the direction in which theassembly 10 is bent away from the neutral orientation.

The assembly 10 with the directional bending stiffness can be utilizedin other applications to achieve the benefits of a low resistance tobending in one direction and a high resistance to bending in the otherdirection. For example, the assembly 10 could be incorporated intoathletic equipment to improve the athlete's on-field performance andreduced fatigue by incorporating such materials into their equipment.The assembly 10 could be incorporated into baseball gloves and/or soccergoalie gloves. When glove fingers, for instance, are pulled in theinward direction, the glove fingers are easily flexed, while if thefingers are bent backwards toward the back of the hand, the fingers ofthe glove are more rigid to resist the bending. A baseball catcher orsoccer goalie, for instance, could integrate the material into theirrespective forms of gloves, whereby the increased stiffness is usedadvantageously to help cushion impact, whilst the increased flexibilityaids with gripping action and easy closure. The asymmetric beamconfiguration of the assembly 10 can protect an athlete, for instance,against hyperextension of their fingers when stopping a soccer ball or abaseball glove that allows easy closure, as well as provide stiffness inglove finger areas with which to stop balls thrown at high velocity. Theasymmetric beam configuration of the assembly 10 could also beincorporated into joint areas of prosthetics, into back or articulatingbraces and supports, or into other medical devices or medicalappliances.

The assembly 10 in accordance with other embodiments can be used as aprotective member that protects a user's excessive bending in anundesired bending, while allowing bending in the opposite direction. Forexample, movement of the limbs and joints of the body outside of theirexpected range of motion is known as hyperextension, which refers tomovement beyond normal limits of angular, rotational or gliding motion,depending upon the anatomical structures involved. The assembly 10 canalso be used in footwear, such as soccer, rugby, or football shoes,configured to flex and bend with a user's foot in one direction during anormal running or walking stride, while maintaining stiffness andresistance to bending in the opposite direction, such as while kicking asoccer ball, rugby ball, or football. Accordingly, when a player kicksthe ball, the shoe remains substantially stiff so as to impart greaterloads or forces to the ball. One or more embodiments of the assembly 10can be specifically tuned for particular athletic events, and/or forparticular athletes or other users. For example, the assembly 10 couldbe used in footwear and tuned based upon an athlete's particularindividual musculoskeletal characteristics, such as metatarsophalangeal(MTP) range of motion and extension velocity while running, so as toprovide a progressive bending stiffness for the athlete to enhance theathlete physical performance. For example, footwear for an athlete witha lager MTP extension could include an assembly 10 tuned to provide aprogressive increase in bending stiffness to help maximize individualperformance. Tuning of shoes for stiffness to a runner's particularcharacteristics can be provided to maximize performance. Assembly 10will adjust the stiffness to different phases of a running(acceleration, sprinting, and jogging) to optimize performance. Forexample, a shoe with a progressive stiffness that exhibits low gearingin the initial acceleration and transitions to a higher gearing at thetop speed phase of the run.

Hyperextension can result in physical injury due to the increased stressand forces applied to ligaments and connective tissues. Hyperextensionoften occurs in concert with physical or sports activities, but can alsodevelop over time through chronic or repetitive overuse of some part ofthe body. For example, lateral epicondylitis or “tennis elbow,” iscaused by the repetitive use of the extensor muscles of the forearm andis commonly associated with playing tennis, but the condition has alsobeen called “washer woman's elbow,” reflective of an age when clotheswashing was performed as a manual vocation. On the same note,chondromalacia patellae or “runners knee,” is the increaseddeterioration and breakdown of the cartilage under the kneecap due to anoverworking of the knee, often due to running, but could be attributedto gymnastics, cycling, horseback riding, ballet, and even swimming.Finally, metatarsophalangeal joint sprain or “turf toe,” occurs when thetoes of the foot are hyperextended, as often occurs in professionalsports that are played on artificial turf, especially football, but hasbeen observed in soccer, rugby, and volleyball, and even in non-fieldsports, like basketball and taekwondo.

Taking “turf toe” as a specific example, the risk of incurring ametatarsophalangeal joint sprain increases with the angle oflongitudinal deflection at the metatarsal phalangeal joint. A sprain canoccur with the hyperextension of any of the toes, although the big toenormally suffers injury, as the bulk of forward dorsiflexive motion isborne by that toe. This type of injury with the metatarsal phalangealjoint region of the foot includes the ligaments and connective tissuesthat join the ball of the foot with the toes. The metatarsal phalangealjoint can be injured if the back of the calf is pushed forward whilstthe knee and toes are in contact with the ground. Injury can also happenwhen the cleats of an athletic shoe grip into artificial turf and failto release the foot when the individual is running or walking. Theforward momentum of the body causes the foot to bend too far forward atthe metatarsal phalangeal joint while the toes are still held firmly inplace by the turf, resulting in hyperextension of the toes.

The risk of incurring injury due to hyperextension can be significantlydecreased through the use of protective equipment that cushions fromdamage or restricts or limits the movement of the various limbs andjoints of the body, whether elbows, wrists, fingers, knees, ankles,toes, hips, or other anatomical structures, to their normal range ofexpected motion. For instance, existing measures for protecting againstturf toe are lacking. For example, U.S. Pat. No. 5,772,621 discloses aturf toe brace that includes a flexible boot adapted for snuglyanchoring the brace to a foot, an elongate non-stretchable strapjoinable to the boot, and a toe loop that is joined to the strapopposite the boot. In use, the strap passes under the foot and isconnected to the boot in such a manner as to pull downwardly on the bigtoe and help prevent hyperextension, whilst the other four unrestrainedtoes remain at risk of hyperextension. As well, the brace requiresenough clearance in the ankle region to fit within a shoe. Last, thestrap could become undone during use, thereby obviating any protectivebenefits.

U.S. Patent Appl. Pub. No. 2012/0240431 discloses a turf toe terminator,which is a semi flexible shoe insert that is inserted into a cleat orsneaker, or is created as part of a shoe, to help prevent injury due tohyperextension of the big toe. A nylon strap is attached to the toe andheel of a polypropylene plastic shoe insert using nylon string. Thenylon strap is attached under tension to generate an inverted arch inthe shoe insert, which helps provide support to a hyperextended big toe.During use, when the toes are forced upward, the nylon strap of the shoeinsert prevents the toes from extending to hyperextension and transferspressure from the toes to the heel of the shoe by pushing downward.However, the strap is attached to the shoe insert with string and istherefore susceptible to breakage. Moreover, the shoe insert isprimarily focused on protecting the big toe with only incidentalhyperextension prevention being provided to the other toes of the foot.

Accordingly, there is a need for a shoe, shoe insert or foot supportthat will safeguard all of the toes of the foot from hyperextensionwhile allowing bending of the toes through the normal range of motionwithout reaching the point of hyperextension. There is a further needfor a protective equipment that keeps body motion, not just the toes,within a normal range of expected motion without restricting normal freemovement up to the limits of hyperextension.

At least one embodiment of the assembly 10 of the present technology isconfigured to significantly decrease or eliminate the risk of turf toeor other metatarsophalangeal joint sprain to all of the toes byincorporating an anisotropically-flexible area into the flex region 110of the footwear under the metatarsal phalangeal joints of the foot. Theanisotropically-flexible area is incorporated into a shoe insert,insole, midsole or outsole and is separated into a dorsal side and aplantar side, both of which are constructed from two different types offlexible material. The material used in the plantar side has a variablemodulus of elasticity tuned to limit longitudinal deflection based onangular deflection levels in the dorsal direction based on angularrotation of the metatarsal phalangeal joint, that is, forwarddorsiflexive motion, while the material used in the dorsal side has amodulus of elasticity that is comparatively higher than the variablemodulus of elasticity of the flexible material of the plantar side.

One embodiment provides a tuned plate assembly made of the assembly 10and incorporated within the shoe sole assembly or provided as an insoleshaped to fit within the bottom part of a shoe. The tuned plate assembly10 has an anisotropically-flexible area situated for placement under themetatarsal phalangeal joint region of the foot. The assembly 10 providesa shoe sole and/or insole with a flexural modulus that increases as afunction of increasing bend angle relative to the neutral orientation.

Furthermore, in the foregoing embodiments, the tuned plate assembly mayalso be configured with a dorsal side exhibiting a variable modulusbehavior, such that the modulus increases as angular rotation(dorsiflexion) of the metatarsal phalangeal joint region occurs, wherethe mechanism creating the dorsal variable modulus is a compressivelayer engagement that coincides with dorsiflexion of the metatarsalphalangeal joint.

The directional bending stiffness described herein can be utilized infootwear-related applications, such as shoe inserts, articles offootwear with a shoe insert, articles of footwear with a midsole,articles of footwear with an outsole, and articles of footwear,requiring a varying resistance to bending in the dorsal direction basedon angular rotation of the metatarsal phalangeal joint. The directionalbending stiffness can also be utilized in applications that provideprotective equipment to keep body movement within a normal orconstrained range of expected motion without restricting normal, freemovement up to the limits of hyperextension, such as needed in the jointareas of prosthetics, back or articulating braces and supports, andarticulating braces.

FIG. 15 is a schematic illustration of a shoe insert 100 for an articleof footwear, in accordance with an embodiment of the present technology.The shoe insert 100 is configured to substantially block or preventmetatarsophalangeal joint sprain due to hyperextension of the toes of awearer's foot 102, thereby significantly decreasing or even eliminatingthe risk of a toe injury. The shoe insert 100 provides ananisotropically-flexible area in the region under the metatarsalphalangeal joints of the foot 102. The shoe insert 100 can be shaped tofit within a shoe, or as part of the shoe's sole assembly. The shoeinsert 100 could be configured as another article of footwear, forinstance, as a sock or foot sleeve. Alternatively, theanisotropically-flexible area defined by the shoe insert 100 could beincorporated into a midsole or outsole of a shoe's sole assembly toprovide the same type of hyperextension prevention.

The shoe insert 100 is a joined assembly having one or more layers witha construction substantially similar to the assembly 10 discussed above.The shoe insert 100 has a dorsal (or upward-facing) layer 104 that fitsconformably and comfortably against or adjacent to the bottom of thewearer's foot 102 and a plantar (or downward-facing) layer 106 that fitssnuggly against the top of the shoe's sole or as part of the sole. Theshoe insert 100 can be used with or in an article of footwear 50discussed above (FIG. 12). The plantar layer 106 generally providescushioning of the foot 102, and the dorsal layer 104 protects the foot102 against chafing, as well as providing a lesser degree of cushioning.

The risk of incurring a metatarsophalangeal joint sprain increases withthe angle of longitudinal deflection at the metatarsal phalangeal joint108 of the foot 102 and often happens if deflection exceedsapproximately 56°. The precise angle of deflection that results in sucha sprain, however, will depend upon many factors, including footplacement and orientation, speed and force of forward movement, physicalstructure of the individual's foot, and any prior metatarsophalangealjoint sprains or foot injuries. The shoe insert 100 is configured tocounter undue deflection that could lead to hyperextension of themetatarsal phalangeal joint 108. The shoe insert 100 incorporates ananisotropically-flexible area 110 situated for placement under themetatarsal phalangeal joint 108 of the foot 102. In general, anisotropicmaterials exhibit directionally-dependent properties, such that thedegrees of flexibility and stiffness differ depending upon the axes atwhich they are measured.

In the shoe insert 100, the flexing of a shoe is measured in torquewhere the shoe is flexed about the flex area 110 generally between theforward and rear portions 116 and 118, and the resistance of the shoeflex increases with flex angle due to increasing flexural modulus. FIG.16 is a graph showing the relationship of the flexural modulus 124 as ashoe flex torque and angle of curvature. The x-axis represents the bendangle of the shoe insert 100 in the dorsal (upward) direction. They-axis represents shoe flex torque in Newton-meters (Nm) and therelationship of flexural modulus that creates the increase in torque.The increase in flexural modulus 124 is caused by curved columns whichare either formed through applied stress (i.e. prebuckling) or weavecrimp, as further described infra, that are formed at a predeterminedangle or through controlled thermal contraction, which set a level ofmaximum permissible angle rotation of the shoe sole about the flex area110. The increase in flexural modulus can thus be described as the ratioof the secondary slope to the primary slope, where the primary slope canbe as low as 100 pounds per square inch (psi) and the secondary slopecan be as high as 33 million psi. Here, the minimum ratio in a materialis approximately 1.25:1 and the maximum ratio is approximately 20:1. Inaddition, the primary slope can be located between 0° and 15° and thesecondary slope can be located beyond approximately 60°. Other ratiosand flex range locations are possible. For example, a shoe insert 100can be configured with the material of the assembly having a ratio ofthe secondary slope to the primary slope defining the flexural moduli inthe range of approximately 1.25:1 to 2.5:1. In another embodiment, theratio can be in the range of approximately 2:1 to 3:1, 2.5:1 to 4:1, 3:1to 6:1,5:1 to 10:1, 6:1 to 13:1, or 10:1 to 20:1.

The shoe insert 100 can use different types of flexible and non-flexiblematerials that are combined to control the location and orientation ofthe flex area 110. FIG. 17 is a cross-sectional view showing theconstruction of the shoe insert 100 of FIG. 15, wherein the dorsal layer104 is formed of one or more rigid sheets 126 of material, while theplantar layer 106 is formed of one or more flexible sheets 128 ofmaterial, exclusive of the flex area 110, with tunable rigid layers 112of material formed in-between the two rigid and non-rigid layers 126,128. Alternatively, the shoe insert 100 could be constructed with just asingle layer of materials, except for the flex area 110, that helpsrestrict excessive bending of the wearer's foot.

The tunable rigid layers 112 of material have a construction similar tothe assembly 10 discussed above, but inverted, wherein the tunable rigidlayers 112 have a dorsal side 130 and a plantar side 132. The materialused in the dorsal side 130 has a modulus of elasticity tuned to limitlongitudinal deflection based on angular rotation of the metatarsalphalangeal joint 108 in the dorsal direction, that is, forwarddorsiflexive motion. The material used in the plantar side 132 has amodulus of elasticity that is comparatively higher than the modulus ofelasticity of the flexible material of the dorsal side 130.

Referring again to FIG. 15, the flex area 110 is configured to have anupwardly curved shape when the joined assembly 10 forming the flex area110 is in the neutral orientation. Accordingly, when the entire shoeinsert 100 is in a neutral configuration, the forward portion 116 wouldbe an angle of approximately 50-56 degrees (or other selected angle)relative to the rearward portion 118. When the forward and rearwardportions 116, 118 are flat and coplanar (FIG. 17), the fiber-basedcomposite material on the plantar side of the flex area 110 would notsubstantively resist bending until reaching the 50-56 degree angle. Theflex area 110 can be tuned and configured to begin providing bendingresistance as the flex area 110 reaches the 50-degree angle, andsignificantly increasing the bending resistance as the flex area 110approaches the 56-degree angle, so as to effectively block or preventthe wearer's toes from flexing past 56-degrees. The plantar side of theflex area 110, however, would be in tension and would bias or urge theflex area 110 back toward the neutral orientation. This biasing of theshoe insert toward the 50-56 degree angle could actually provide someenergy return to the wearer's foot during a stride cycle as the footapproaches the toe-off phase, all while preventing over bending andhyperextending of the metatarsal joints.

The flex area 110 is preferably situated for placement under metatarsalphalangeal joints 108 (FIG. 15) to provide optimal protection fromhyperextension of the toes. In the average person, the flex area 110would be placed in the region located at about 70% of the total shoeinsert length (measuring from the heel to the toes). The rigid layers112, that is, the areas outside of the flex area 110 on the plantaraspect of the shoe insert 126, should preferably be more rigid than theflex area 110, so as to help prevent the plantar aspect of the foot 102from flexing in the areas outside of the flex area 110.

The shoe insert 100 lowers or eliminates the risk of incurring ametatarsophalangeal joint sprain (“turf toe”) by preventing longitudinaldeflection of the foot 102 at the metatarsal phalangeal joint 108 beyondapproximately 56°. The shoe insert 100 incorporates ananisotropically-flexible area 110 formed using a fiber-reinforcedcomposite material that exhibits a different modulus of flexibility whena predetermined angle of flexion has been reached. Flexing of thematerial beyond the predetermined angle is limited or precluded, whilepreserving pliability of the material within the predetermined angle.This type of anisotropically-flexible area can be incorporated intoother forms of protective equipment intended to keep body movementwithin a normal or constrained range of expected motion withoutrestricting normal free movement up to the predetermined angle, such asin the joint areas of prosthetics, back or articulating braces andsupports, and articulating braces. The shoe insert 100 configured tocontrol excessive bending in the toe region to help prevent turf toe canhave a flexural moduli with a ratio in the range of approximately 1.25:1to 2.5:1. In another embodiment the ratio can be in the range ofapproximately 2:1 to 3:1, 2.5:1 to 4:1, 3;1 to 6:1, 5:1 to 10:1, 6:1 to13:1, or 10:1 to 20:1.

Components of the shoe insert 100 coupled to the flex area 110 can bemade of a metal, polymer, composite, or combination thereof. In general,the strengths and stiffness of fiber-reinforced composite materials whenused in the layers of the shoe insert 100 are dependent on theproperties of the type of fiber, the orientation of the fiber, and thematrix used with the fiber. In one embodiment, the material used in thelayers of forming the dorsal side 130 of the tunable rigid layer 112 isa carbon fiber epoxy plate, and the material used in the plantar side132 is either a nitrile butadiene rubber, polyurethanes, or acrylics, orthermoplastic polyurethane films or elastomeric films that are joined tothe surface of the flexible fiber substrate defining the dorsal side130. Other types of materials are possible; however, the modulus ofelasticity of the material used in the plantar side 132 must increase inmodulus based on the angular rotation of the metatarsal phalangeal joint108. The material used in the dorsal side 130 must also be higher inmodulus than the plantar side 132 to minimize the bending of the arch ofthe foot and to provide the flex area 110 of the shoe insert 100 withthe necessary anisotropically-flexible properties.

In one embodiment, to construct the shoe insert 100, base carbon fiberfabric is first impregnated with elastomeric binders. The impregnatedcarbon fiber fabric is then dried until the solvents are removed. Dryingtime depends upon the solvent ratio and drying temperature. The contentof the impregnating elastomeric binders can range from 0.5-50%, butpreferably falls within the range of 5-23%, which is dependent upon themodulus ratio desired. No binder can exhibit similar behavior. FIG. 18is a diagram showing the layered construction of a non-rigid flexiblecarbon fiber composite 136. An impregnated carbon fiber fabric 138 inone embodiment is pressed at 325° F. at 6 psi for 10 minutes between twosheets 0.004 inch thick films, top 140 a and bottom 140 b. This processproduces a non-rigid flexible carbon fiber composite 136.

FIG. 19 is a diagram showing the layered construction of a compositelaminate 142. Each carbon fiber composite laminate 142 is comprised oftwo or more layers of the non-rigid flexible carbon fiber composites 136joined to one or more rigid carbon fiber plates or other rigidsubstrates. In one embodiment, on the dorsal layer 104 of the shoeinsert 100, a 0.093 inch thick polycarbonate layer 144 is heat pressedto two sheets of the non-rigid carbon fiber composite 136 at atemperature of 300° F. at 6 psi for 10 minutes. On the plantar layer 106of the shoe insert 100, the two sheets of the non-rigid carbon fibercomposite 136 are heat pressed to two pieces of 0.030 inch thick rigidcarbon fiber plates 146, or other rigid substrates, such as metal orplastic, at a temperature of 300° F. at 6 psi for 10 minutes. The rigidcarbon fiber plates 146 are spaced 1.25-1.5″ apart to form a gap thatserves as the flex area 110. The newly-formed laminate carbon fiberepoxy plate is allowed to cool to 180° F. before removal from the press.

The coefficient of thermal expansion of polycarbonate at 300° F.provides enough shrinkage upon cooling to create a curved column.Non-rigid carbon fiber composites 136 are limited by their compressionstrength and under compressive loading can form curved columns, whichare small bends in the material. FIG. 20 is a diagram showing, by way ofexample, column bending in a non-rigid carbon fiber composite 136. Whenthe composite material is flexed away from the neutral orientation,thereby putting the non-rigid carbon fibers of the woven carbon fiberfabric 138 into tension, curved columns begin to straighten until apoint of straightness at which point the material rapidly increases themaximum tensile loading. This characteristic enables the carbon fibercomposite material 136 to be pre-stressed through the curved columns,such that flexing of the material beyond a predetermined angle can belimited or precluded, while preserving pliability before reaching thepredetermined angle. The curved columns are formed in the non-rigidcarbon fiber composite 136 at a predetermined angle that sets the levelof curvature in the curved column; when the non-rigid carbon fibercomposite 136 is flexed away from the neutral orientation and the curvedcolumns are placed in tension, the flexural modulus significantlyincreases, thus enabling the non-rigid carbon fiber composite 136 tofixedly engage or “lock out” further flexion. As the non-rigid carbonfiber composite 136 combines one or more sheets of the non-rigidflexible carbon fiber, breaking or failure of the composite material isprecluded, as the degrees to which curved columns are formed will differas between the individual sheets of the non-rigid flexible carbon fiberwith the result that the curved beams of the different sheets toleratecompression, up to the predetermined angle.

The control of temperature and the use of various substrates exhibitingdifferent levels of coefficients of expansion can produce varyingamounts of contraction upon cooling to create a desired amount ofcurvature. The curvature in the column allows the polycarbonatesubstrate, or other lower modulus flexible materials, to provide thebending stiffness desired and the subsequent straightening of the curvedcolumn material imparts a strain stiffening behavior of the resultantflexible composite material.

In a further embodiment, to construct the shoe insert 100, the basecarbon fiber fabric 138 is first impregnated with elastomeric binders.The impregnated carbon fiber fabric 138 is then dried until the solventsare removed. Drying time depends upon the solvent ratio and dryingtemperature. The content of the impregnating elastomeric binders canrange from 0.5-50%, but preferably falls within the range of 5-23%,which is dependent upon the modulus ratio desired. This material hassubstantially the same form of layered construction as the non-rigidflexible carbon fiber composite 136 described supra with reference toFIG. 18. The impregnated carbon fiber fabric is pressed at 325° F. at 6psi for 10 minutes between two sheets 0.004 inch thick films, top andbottom. This process produces a non-rigid flexible carbon fibercomposite.

Each assembly is a laminate stack that is composed of two or more sheetsof the non-rigid flexible carbon fiber composites and titanium alloy orother rigid substrates. FIG. 21 is a diagram showing the layeredconstruction of the laminate stack 150. In one embodiment, on theplantar layer 106 of the shoe insert 100, two sheets of the non-rigidcarbon fiber composite 136 are heat pressed to a 0.043 inch thickpolycarbonate layer 151 at a temperature of 300° F. at 6 psi for 10minutes. The pressed laminate stack 150 is then laid onto a 0.012 inchthick titanium alloy 152 and a 0.020 inch polycarbonate 153 is adheredusing a 0.004 inch thick thermoplastic polyurethane film. The combinedlaminate stack 150 is hot pressed at a temperature of 300° F. at 6 psifor 10 minutes and allowed to cool to 180° F. before removal from thepress.

Next, the laminate stack 150 is heat formed to an angle of about 56°about a 1.5 inch radius in the desired flex area. Note that an angle ofabout 56° is applicable to a shoe insert that helps to prevent “turftoe.” Different angles may be appropriate to other applications, such asan elbow brace that limits movement during rehabilitation followingsurgery. The non-rigid carbon fiber fabric 136 is convex to the laminatestack 150. The laminate stack 150 is heat formed though localizedheating to form the 1.25 inch to 1.5 inch flex area over the radiususing an infrared heating source, a conductive heating block, ordirected hot air. The heat forming stretches the flexible carbon fiberfabric's sheets based on their distance from the axis of flex. FIG. 22is a diagram showing the change in length of each layer 155, 156, 157 inthe laminate stack 150 as the radius 158 changes from the originalnatural axis. The length of each successive layer moving inward towardsthe axis of flex is shorter than the preceding layer. After the laminatestack 150 is heat formed, the laminate stack 150 is restored to asubstantially flat form and the layers 155, 156, 157 in the area of heatforming 160 are placed under compression to form curved columns withinthe flex area.

In a still further embodiment, to construct the shoe insert 100, basecarbon fiber fabric is first impregnated with elastomeric binders. Theimpregnated carbon fiber fabric is then dried until the solvents areremoved. Drying time depends upon the solvent ratio and dryingtemperature. The content of the impregnating elastomeric binders canrange from 0.5-50%, but preferably falls within the range of 5-23%,which is dependent upon the modulus ratio desired. This material hassubstantially the same form of layered construction as the non-rigidflexible carbon fiber composite 136 described supra with reference toFIG. 18. The impregnated carbon fiber fabric is pressed at 325° F. at 6psi for 10 minutes between two layers 0.004 inch thick films, top andbottom. This process produces the flexible non-rigid carbon fibercomposite 136.

Each assembly is composed of one or more layers of the non-rigidflexible carbon fiber composites 136 and a rigid substrate ofpolycarbonate or titanium, or a rigid composite plate. FIG. 23 is adiagram showing the layered construction of a carbon fiber joined plate164. In one embodiment, on the plantar layer 106 of the insert 100, twolayers of the non-rigid carbon fiber fabric 138 are placed on top of a0.020 inch thick rigid substrate 164 of polycarbonate or titanium, or arigid composite plate. The layered pieces are then placed between twosheets of release paper and heat formed. FIG. 24 is a diagram showing aheat forming tool 166 for use with the carbon fiber joined plate 164 ofFIG. 23. The layered pieces placed into the heat forming tool 166, whichis then heated. The apex of the curve 168 in the center of the flex area110 (FIG. 17) of the sole is formed into the base of the tool 166. Thelayered pieces are heat pressed at a temperature of 300° F. at 6 psi for10 minutes, and then cooled to 180° F. before removal from the press.

In a yet further embodiment, a layer of unidirectional fiber tape isimpregnated with elastomeric binders and joined to a rigid substrate ofpolycarbonate or titanium, or a rigid composite plate, such as describedwith reference to FIG. 23. The joined unidirectional fiber tape is thenplaced between two layers of the non-rigid carbon fiber composite 136and heat formed though localized heating or shaped using a heat formingtool 166, which stretch the fiber layers to create curved columns.

Metals or plastics such as titanium and polycarbonate can be stamped ormolded with shapes, slits, and perforations. Shapes can include but arenot limited to pre-shaped buckles and bumps. Slits can be straight orcurved in a staggered or array pattern. Perforations can be circles,ellipses, rectangles or squares.

The two components of the shoe insert 100 are joined together to form ajoined beam through laminating temperatures ranging from 200° F. to 375°F. for about ten minutes or less and a pressure ranging from 2 psi to 8psi, but is dependent upon the material melting point and its ability toflow. The resulting joined beam exhibits an increase in modulus based onangular rotation of the metatarsal phalangeal joint 108 in the flex area110 (FIG. 14). The increase in modulus exponentially increases in highbending stiffness (moduli) until about an angle of 56°, after which arapid rise in stiffness or a locking of the materials prevent the flexarea 110 from bending any further, thereby protecting the metatarsalphalangeal joint 108 (FIG. 15) from hyperextension.

Different configurations and combinations of fiber, such as carbon,glass, Kevlar, composite materials, metal foils, and plastic sheets canbe advantageously used in the tunable rigid sheets 112 to construct theanisotropically-flexible area 110. The flex experienced by footwear whencombined with a shoe insert 100 can be empirically measured using adynamic flexion shoe flexion device, such as the Shoe Flexer product,manufactured by Exeter-Research, Inc., Brentwood, N.H., whichdynamically flexes each shoe while measuring the torque required to flexabout the flex area 110. A three-point bend on such ananisotropically-flexible shoe insert 100 at the flex area 110 can beused to measure torque (moments) at angles below 25° quasi-staticallyfor low torque angle measurements. FIG. 25 is a graph 170 showing, byway of example, the differences between flexural moduli in exemplarytesting configurations. The x-axes represent flex angle in degrees. They-axes represent torque in Nm. The empirical testing was conducted usinga shoe equipped with an anisotropically-flexible shoe insert 100 at theflex area 110 that achieved dynamic testing results not reached intraditional football cleat construction with 60 Nm at 60° of flex angle.Conventional football cleat technology has torque values of 16-18 Nm at75° of flex angle. The dynamic flex tester flexes the shoe at a rate of600-800 degrees per second. The flex test data demonstrates control ofincreasing torque at controlled flex angles based on construction andmaterials in the flex area 110.

The range of motion stiffness can be tuned through variation in modulicombinations and laminate construction. The moduli can be changed basedon resin matrix modulus, fabric weave pattern, and fiber orientation.FIGS. 26A and 26B are illustrations showing, by way of examples,controlled curvature in columns in a non-rigid carbon fiber material172, 174 under pre-compression through thermally controlled contraction,by pre-forming to a predetermined engagement angle and by segmentedwedges (or partial cuts or cut-through designs) with combined anglesachieving 56° flex angle and fully engaging the non-rigid carbon fiberat a predetermined lock-out angle. The segmented wedges, partial cuts orcut-through designs are formed into the shoe insert 100 such that themodulus of elasticity remains low until the segmented wedges, partialcuts or cut-through designs compress into a substantially solidstructure after which the modulus of elasticity increases. By changingthe matrix modulus, the buckling resistance will change, thereforechanging the engagement point of the material. The matrix modulus canvary between less than 50 psi to greater than 300,000 psi.

The engagement point is variable, based on the level of contraction orpreformed angle. The amount of curvature in the column at each level canbe adjusted by varying the number of sheets of fibers and controllingwhether the fibers are unidirectional or weaved. For example, atwo-layer non-rigid carbon fiber material that has been joined to a highmodulus substrate will have an inner layer of carbon fiber materialjoined against the high modulus substrate with a lower level ofcurvature in the column and an outer layer of carbon fiber material withhigher amounts of curvature in the column that engage at differentangles of rotation. The combination provides a varying modulus ofelasticity as the fibers become more and more engaged under strain.

The engagement point also changes based on the weave density. Weavedensities affect weave crimp by changing the spacing of the transversetows, thereby changing the column length for buckling during thermal orpreformed curvature control. For example, a 268 gsm fabric will haveapproximately 16 tows per inch, which yields a tow spacing of 0.0625inches and with a 2×2 twill pattern gives a 0.125 inch column length. A200 gsm fabric will be 12.5 tows per inch, which yields a tow spacing of0.080 inches and with a 2×2 twill pattern gives a 0.160 column length.Shorter column lengths decrease the amount of flex angle engagementwhile longer column lengths increase the amount of flex angleengagement. Other suitable weave pattern, densities and fiber weightsare possible. For example, tow or fiber bundle diameters may vary basedon the number of filaments in the bundle, and common carbon fiber bundlesizes have a range of 1,000 to 50,000 filament fibers.

Referring back to FIG. 25, the torque should target below 10-12 Nm inathletic footwear at up to 25° of flex. The lower the value becomes, themore freely the metatarsal phalangeal joint is able to rotate, whichminimizes fatigue. The torque value should increase up to 30 Nm at up to56° of flex, and beyond 56° of flex, the torque value should meet orexceed 60 Nm at up to 75° of flex. FIG. 25 also shows a comparison ofdifferent constructions of the flex test with plate construction onlywithout the shoe being tested and in static test versus the shoe testbeing tested in dynamic. The values of the plates can be controlledthrough all zones with increasing of stiffness through the active zoneand with a rapid increase in stiffness beyond 60° of flex. Shifting thefabric can increase the modulus in tension as the fibers orient duringstrain, which decreases the fiber angle and aligns with the load toincrease in strength.

In a further embodiment, an anisotropically-flexible beam can beconstructed as a weave pattern and unidirectional fibers that providediffering moduli based on weave direction and fiber orientation. Thismaterial changes layer orientations of the non-rigid material to providestrain-stiffening behavior as discussed above.

While the invention has been particularly shown and described asreferenced to the embodiments thereof, those skilled in the art willunderstand that the foregoing and other changes in form and detail maybe made therein without departing from the spirit and scope of theinvention.

Remarks

The above description and drawings are illustrative and are not to beconstrued as limiting. Numerous specific details are described toprovide a thorough understanding of the disclosure. However, in someinstances, well-known details are not described in order to avoidobscuring the description. Further, various modifications may be madewithout deviating from the scope of the embodiments.

Reference in this specification to “one embodiment” or “an embodiment”means that a particular feature, structure or characteristic describedin connection with the embodiment is included in at least one embodimentof the disclosure. The appearances of the phrase “in one embodiment” invarious places in the specification are not necessarily all referring tothe same embodiment, nor are separate or alternative embodimentsmutually exclusive of other embodiments. Moreover, various features aredescribed which may be exhibited by some embodiments and not by others.Similarly, various requirements are described which may be requirementsfor some embodiments but not for other embodiments.

The terms used in this specification generally have their ordinarymeanings in the art, within the context of the disclosure, and in thespecific context where each term is used. It will be appreciated thatthe same thing can be said in more than one way. Consequently,alternative language and synonyms may be used for any one or more of theterms discussed herein, and any special significance is not to be placedupon whether or not a term is elaborated or discussed herein. Synonymsfor some terms are provided. A recital of one or more synonyms does notexclude the use of other synonyms. The use of examples anywhere in thisspecification, including examples of any term discussed herein, isillustrative only and is not intended to further limit the scope andmeaning of the disclosure or of any exemplified term. Likewise, thedisclosure is not limited to various embodiments given in thisspecification. Unless otherwise defined, all technical and scientificterms used herein have the same meaning as commonly understood by one ofordinary skill in the art to which this disclosure pertains. In the caseof conflict, the present document, including definitions, will control.

We claim:
 1. An anisotropic bendable plate assembly comprising: a firstlayer of flexible material having a plurality of arranged fibers,wherein the first layer has a first rigidity, a first tensile modulus,and a first compressive modulus lower than the first tensile modulus;and a rigid second layer fixedly connected to the first layer in asubstantially parallel orientation, the second layer having a secondrigidity greater than the first rigidity; wherein the plate assembly iselastically bendable in a first direction with an outer surface of thefirst layer being in compression, with the plurality of arranged fiberselastically buckled, and the plate assembly is elastically bendable in asecond direction opposite the first direction with the outer surface ofthe first layer being in tension, and the plate assembly has a firstbending stiffness during bending in the first direction and a secondbending stiffness greater than the first bending stiffness duringbending in the second direction.
 2. The plate assembly of claim 1wherein the arranged fibers are at least partially embedded in a matrixmaterial.
 3. The plate assembly of claim 1 wherein the first layercomprises a binder material and wherein the arranged fibers are at leastpartially impregnated with the binder material.
 4. The plate assembly ofclaim 1 wherein the first layer comprises a thermoplastic film coupledto the arranged fibers.
 5. The plate assembly of claim 4 wherein thethermoplastic film comprises polyurethane.
 6. The plate assembly ofclaim 4 wherein the thermoplastic film is positioned between thearranged fibers and the second layer.
 7. The plate assembly of claim 1wherein the first layer comprises a plurality of sheets of the arrangedfibers joined together.
 8. The plate assembly of claim 1 wherein thesecond layer comprises a composite fiber material.
 9. A sole assemblyfor an article of footwear, the sole assembly comprising: an outsole; amidsole coupled to the outsole; and an anisotropic plate assemblypositioned adjacent to the midsole, the plate assembly comprising: anupper layer having a first rigidity, a first tensile modulus, and afirst compressive modulus different than the first tensile modulus,wherein the upper layer is configured to elastically buckle undercompression and wherein the upper layer comprises a plurality ofarranged fibers at least partly encapsulated in a matrix material; arigid lower layer having a second rigidity greater than the firstrigidity, and having a second tensile modulus and a second compressivemodulus substantially the same as the second tensile modulus; and athermoplastic film arranged between the upper and lower layers, wherein—the upper and lower layers are joined together at an interface areadefined by the thermoplastic film, the plate assembly is elasticallybendable in opposing first and second directions, wherein an outersurface of the upper layer is in compression during bending in the firstdirection and in tension during bending in the second direction, and theplate assembly has a first bending stiffness during bending in the firstdirection and a second bending stiffness greater than the first bendingstiffness during bending in the second direction.
 10. The sole assemblyof claim 9, further comprising a neutral bending plane substantiallyparallel to the interface area.
 11. The sole assembly of claim 9 whereinthe lower layer comprises a rigid fiber-reinforced composite material.12. The sole assembly of claim 9 wherein the upper layer comprises awoven fabric of fibers having an offset angle.
 13. The sole assembly ofclaim 9 wherein the upper layer comprises a fabric with a weave patternhaving a first fabric tensile modulus in one direction and a secondfabric tensile modulus different than the first fabric tensile modulusin a direction substantially transverse to the one direction andsubstantially in the same plane.
 14. The sole assembly of claim 9wherein the first direction is plantar flex direction and the seconddirection is a dorsal flex direction.
 15. The sole assembly of claim 9wherein the lower layer comprises a rigid composite fiber material thatincludes woven fibers embedded within a matrix.
 16. An anisotropiccomposite material assembly, comprising: a first layer comprising aplurality of sheets of fabric joined together and each having firstfibers interlaced with second fibers at a selected angle relative to theeach other, wherein the first layer has a first rigidity, a firsttensile modulus, and a first compressive modulus, and wherein at leastthe first or second fibers in the plurality of sheets of fabric areconfigured to elastically buckle under coplanar compressive loads; arigid second layer joined to the first layer at an intermediateinterface area, the second layer comprising a rigid material having asecond rigidity greater than the first rigidity, and having a secondtensile modulus and a second compressive modulus; and a thinintermediate film at the intermediate interface area and being affixedto the first and second layers, wherein the assembly is elasticallybendable about an axis in a first direction that puts the first layer intension and the second layer in compression, the assembly is elasticallybendable about the axis in a second direction opposite to the firstdirection that puts the first layer in compression and the second layerin tension, and the assembly has a first bending stiffness when theassembly is bent in the first direction and a second bending stiffnessless than the first bending stiffness when bent in the second direction.17. The assembly of claim 16 wherein the intermediate film is athermoplastic film having a thickness of approximately 0.0005-0.025inches.
 18. The assembly of claim 16 wherein the rigid second layercomprises a composite fiber material.
 19. The assembly of claim 18wherein the composite fiber material comprises woven fibers embeddedwithin a matrix.
 20. The assembly of claim 18 wherein the first tensilemodulus is greater than the first compressive modulus and the secondtensile modulus is substantially the same as the second compressivemodulus.